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Playing a sound clip

QuadU

Sep 24, 2012
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Sep 24, 2012
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Hello all,

A friend of mine is going to play Santa Claus in Lapland next winter and I'm helping him to make a letterbox for the kids to post their Christmas letters. The idea is that a sound clip is played when a letter is inserted. My first idea was to reuse a cheap mp3 player, upload one song on it and connect its play button to a mechanical switch. However, the problem is that on almost all mp3 players, the play button also acts as pause button. That will cause the clip to pause when e.g. a bad (double) contact is made or when a new letter is posted while the clip is still playing.
I also looked around for small electronic kits, found the perfect solution in following kit:
http://www.velleman.eu/products/view/?id=407028
But I faced the same problem as also here the play/pause connector pin is shared.

Now I'm looking for an (electronic) solution to make sure that after a contact is made, no new contact can be made for x seconds. This ensures that the clip finished playing before a contact towards the play/pause button can be made again...

Can anyone help me with this?
Alternative solutions are welcome as well of course!

Thanks for your help!
 

Harald Kapp

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Nov 17, 2011
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You can use a monoflop (e.g. based on the 555 timer IC). The monoflop would be triggered by a sensor (mechanical, or optoelectronical) upon insertion of a letter into the box. The output of the monoflop closes the "play" circuit by means of a transistor or photocoupler.
Set the delay of the monoflop to the length of the tune you want to play.
 
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